Modifying live websites in your browser?

Hi everyone I would like to edit an existing website in my internet browser.So when I click the same website I want my browser show me the edited format.Is there any software you know to edit a website (just in my browser) to show me the modified format???????

To edit the site in realtime, you can use Firefox and then install the Firebug extension.
Once Firebug is installed, visit the page, and hit F12.
That opens Firebug and shows you the source code of the site.
Then click the HTML tag
Then click edit.
You are editing in real time, your changes will appear in the browser accordingly.*

These changes are not persistant, meaning the next time you visit the site the source code is pulled from the server again.

If you want the changes to remain permanent for you and your browser only, you will need to use a different extension called Grease Monkey. This allows you to write custom javascripts for the page that are applied each time you visit the page.